The 29-year-old Kottaras will compete for a backup job behind Salvador Perez in Kansas City.

Kottaras hit .220 with 24 homers and 84 RBIs in 249 career games with the
Red Sox,
Brewers and Athletics. He was acquired by Oakland on July 29 and then played in four games during the A's divisional series against the Detroit Tigers.

The 28-year-old Abreu spent most of last season at Triple-A Omaha, hitting .257 in 22 games with the big league club.